Extreme value prediction of nonlinear ship loads by FORM using Prolate Spheroidal Wave Functions

In this study, a method for predicting the extreme value distribution of the Vertical Bending Moment (VBM) in a flexible ship under a given short-term sea state is presented. The First Order Reliability Method (FORM) is introduced to evaluate the Probability of Exceedances (PoEs) of extreme VBM levels. The Karhunen-Loeve (KL) representation of stochastic ocean wave is adopted in lieu of the normal wave representation using the trigonometric components, by introducing the Prolate Spheroidal Wave Functions (PSWFs) to formulate the wave elevations. By this means, reduction of the number of stochastic variables to reproduce ocean wave is expected, which in turn the number of computations required during FORM based prediction phases is significantly reduced. In this study, the Reduced Order Model (ROM), which was developed in our previous studies, is used to yield the time-domain VBMs along with the hydroelastic (whipping) component in a ship. Two different short-term sea states, moderate and severe ones, are assumed. The FORM based predictions using PSWF for normal wave-induced VBM are then validated by comparing with those using the normal trigonometric wave representation and Monte Carlo Simulations (MCSs). Through a series of numerical demonstrations, the computational efficiency of the FORM based prediction using PSWF is presented. Then, the validation is extended to the severe sea state where the whipping vibration contributes to the extreme VBM level to a large degree, and finally the conclusions are given.     

“双一流”建设背景下一流工科课堂建设探讨

“双一流”建设正在如火如荼的开展中,在“双一流”建设的重要机遇下,打造“一流课堂”是提高高等人才整体素质和专业能力的重要途径。通过目前存在的突出问题剖析,提出通过教学内容、教学方法和教学手段三个方面为抓手,进行不断改进和完善传统课堂教学模式,加速推进“一流课堂”建设普遍化,整体提高课堂教学质量,提升学校整体教学水平。     

不同材料嵌体修复邻牙合(Ⅱ类)洞型的三维有限元研究

目的应用三维有限元分析不同材料嵌体修复邻牙合(Ⅱ类)洞型后牙体组织的应力变化趋势。方法采用锥形束CT(CBCT)扫描的方法,应用Mimics、Geomagic逆向工程等软件建立含嵌体修复的邻牙合面(Ⅱ类)洞型三维有限元模型,并求解分析各模型中垂直、侧向力(舌向45°)加载条件下牙体主应力峰值及不同嵌体修复邻牙合(Ⅱ类)洞后牙体的Von-mises应力分布状况。结果建立了包含牙釉质、本质、髓腔以及牙周膜、牙槽骨的精细下颌第一磨牙邻牙合面(Ⅱ类)近中-牙合(MO)洞型不同嵌体修复三维有限元模型。侧向加载(舌向45°)时牙体的应力峰值明显高于垂直加载,2种加载下4种材料应力值按照降序排列为:钴铬合金>金合金>瓷>树脂。4种不同材料对牙体组织的应力分布相似,牙体的应力峰值主要在洞底部牙本质所对应的髓腔处。结论在下颌第一磨牙邻牙合面(Ⅱ类)洞型的嵌体修复中,与其他3种材料相比,树脂嵌体因其与牙体组织更加相近的弹性模量而产生对牙体组织更小的应力,有利于减少牙折等危险。     

Spatial and Temporal Changes in Access Rights to Shellfish Resources in British Columbia

Over the past decade, the shellfish and finfish aquaculture industry has expanded rapidly in coastal British Columbia (BC) Canada. Foreshore and nearshore shellfish and finfish aquaculture leaseholds are sited in close proximity or in direct competition with habitat for wild shellfish. As a result, some wild shellfish harvesters believe shellfish farms are significantly reducing access to beaches and estuarine areas for wild harvesting, or that salmon farms are contaminating wild shellfish stocks. In this article, Geographic Information Systems (GIS) are used to analyze spatial and temporal trends in the growth of shellfish and finfish aquaculture tenures in BC, while interviews with stakeholders in coastal communities are used to explore user conflicts and the implications of changing access rights on the distribution of marine resources. Qualitative and quantitative findings suggest that shellfish aquaculture provides significant economic opportunities for coastal communities, but that such development may hold increased risk of spatial conflicts over marine habitat as the aquaculture industry continues to grow.     

高职英语课堂趣味性教学的实践

本文通过对如何实施高职英语课堂趣味性教学的探讨,提出解决高职学生英语基础差,高职英语教学难状况的有效办法,以此避免学生厌学英语学习,提高高职英语教学质量,保证教学的顺利进行,促进学生的全面发展。     

海洋平台结构系统疲劳可靠性分析的一阶二次矩方法

本文提出了海洋平台结构系统疲劳可靠性分析的一阶二次矩方法，海洋平台结构系统中疲劳破坏的失效途径用一由若于失效单元组成的并闻系统来模拟，失效单元代表了平台结构中易发生疲劳破坏的管节点，文中寻出了失效单元依次破坏时的疲劳寿命与它们在其他单元均未破坏下的疲劳寿命之间的一船关系式，并用一阶二次矩方法计算上述并联系统的失效概率。     

Quasi-dynamic traffic assignment with residual point queues incorporating a first order node model

Static traffic assignment models are still widely applied for strategic transport planning purposes in spite of the fact that such models produce implausible traffic flows that exceed link capacities and predict incorrect congestion locations. There have been numerous attempts to constrain link flows to capacity. Capacity constrained models with residual queues are often referred to as quasi-dynamic traffic assignment models. After reviewing the literature, we come to the conclusion that an important piece of the puzzle has been missing so far, namely the inclusion of a first order node model. In this paper we propose a novel path-based static traffic assignment model for finding a stochastic user equilibrium in general transportation networks. This model includes a first order (steady-state) node model that yields more realistic turn capacities, which are then used to determine consistent capacity constrained traffic flows, residual point (vertical) queues (upstream bottleneck links), and path travel times consistent with queuing theory. The route choice part of the model is specified as a variational inequality problem, while the network loading part is formulated as a fixed point problem. Both problems are solved using existing techniques to find a solution. We illustrate the model using hypothetical examples, and also demonstrate feasibility on large-scale networks.     

"先简支后连续"梁桥的设计及应用

“先简支后连续”体系梁在公路及市政桥梁建设中得到广泛应用。阐述这种结构体系的合理性，重点分析其计算、设计及施工要点。简要介绍其应用现状。     

盐田港集装箱码头二期工程地基处理的施工监理

通过叙述现场试验确定地基处理施工方案的过程,说明施工监理处理设计变更及进行质量控制的方法。     

首件鉴定的实践与体会

首件鉴定是产品质量控制过程的关键环节,从运用首件鉴定程序的实际情况出发,着重阐述产品首件鉴定的范围、时机、鉴定内容,以及在运行首件鉴定过程中遇到的瓶颈及其解决对策,提出针对具体情况进行层次化首件鉴定的理念。